Be nice to our elders.
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You can back up whatever you want to an external/flash drive as well. This is 2012, not 2005.
Because it's about function. Not only that, again, weight. The heavier it is, the more expensive it is to ship. Save on shipping = saving money.
Who is this "everyone"? Not everyone uses an Optical Drive. They don't show the Air with an External next to it in ads.
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Very few people use their iMac as their "TV".
Ripping CDs? They still sell those things?!?
Yes, I could back up to flash drives, and yes, I have several. I also have several external HDDs. However, I can buy a spindle of 100 blank DVD-Rs for about what it would cost me to buy a single 32 gig USB stick. Do you need me to do the math for you for the cost per gig? ok I found both for about $20, not being picky about brands. The USB stick is about $0.63 per gig, while the DVDs are $0.04 per gig. I'll grant you that you can rewrite the flash drive, but I could get DVD-RWs and still maintain a price advantage.
Shipping is a one time cost, which can (and I'm sure is) passed on in part or full to the buyer. How much does a slot loading ODD weigh these days anyway? It cannot be that much.
I don't recall saying 'everyone' uses a ODD, but I'm sure a lot do. Many people still actually buy CDs and DVDs. I get books on CD and listen to them on my iPhone. Rip my kids' DVDs for them to watch on my old iPod Touch.
Let me take your asinine line of thinking a bit further.
If you want to make the argument that 'everyone' must use something for it to be included, I would say take out the web cam, microphone, Thunderbolt, Firewire and USB ports, as well as the audio in/out ports. People don't 'need' those either! If you don't video chat with people or use voice dictation, you don't need the camera or mic. Many people can't afford Thunderbolt accessories, so clearly we don't need those. Firewire is in limited use, cut it. We have a Bluetooth keyboard and mouse, cut the USB. People will just have to use wi-fi enabled printers and network connected storage. Heck, we have iCloud, so you don't need external HDDs at all. I can't imagine why you might need to where headphones or connect to the AUX on a home stereo. We have AirPlay for that after all.
Heck, with your 'everyone' argument, all you really need is a Chromebook. After all, everyone can get by with just checking facebook.
It would be even better if they upgraded to Blu-Ray, but I expect that Steve's word on that will last a bit longer.
I can live without retina, but I would like a minimal SSD included for the OS.